Vacancy Engineering of Ultrathin 2D Materials for Photocatalytic CO₂Reduction

Abstract

Photocatalytic carbon dioxide (CO2) reduction is a sustainable and green strategy for the conversion of CO2 into hydrocarbon solar fuels, whereas its large‐scale application is severely restricted by lack of highly effective photocatalysts. Ultrathin 2D materials with tunable electronic structure display great potential towards photocatalytic CO2 reduction. However, the photocatalytic performance still remains unsatisfied due to high activation energy of CO2 molecules on catalytic sites. To this end, surface vacancy engineering can endow coordinately unsaturated sites as actively catalytic sites for CO2 molecules chemisorption and activation. In this review, we focus on vacancy‐engineered ultrathin materials for CO2 photoreduction. Different vacancies with classified anion vacancies, cation vacancies, vacancy pairs, voids, and their corresponding role in CO2 photoreduction are proposed. The different strategies based on vacancy engineering, including direct modulation of vacancy concentrations, refining vacancy states by heteroatom, and vacancy‐engineered heterostructure, are presented. Finally, the future developments and their associated challenges concerning defective ultrathin 2D materials are discussed.

Zn Dopants Synergistic Oxygen Vacancy Boosts Ultrathin CoO Layer for CO2 Photoreduction

“…In terms of superior photocatalytic performance of common transition metal oxides, many researches have focused on the tuning of oxygen vacancies for improving the photocatalytic properties of the materials. [ 27 ] For instance, Chen et al. had successfully synthesized oxygen vacancy‐laden NiO nanoplatelets with high CO 2 adsorption energy via calcination under Ar protection to optimize the activity and selectivity for CO 2 ‐to‐CO conversion of the normal NiO.…”

Engineering Cocatalysts onto Low‐Dimensional Photocatalysts for CO2 Reduction

“…The local microstructure, coordination environment, and physicochemical property at the surface can be mediated via the construction of various defects. [79][80][81][82] First, vacancy engineering has been used to tailor the AuCu alloy cocatalysts. Through acetic acid treatment, some Cu atoms in AuCu alloy can be etched, and then the Cu vacancies can be engineered into the surface (Figure 8a-h).…”

Emerging Cocatalysts on g‐C3N4 for Photocatalytic Hydrogen Evolution

“…Generally, photocatalytic H 2 evolution on g-C 3 N 4 can be divided into three processes (Figure 1), including light absorption under light irradiation to generate electrons-holes pairs, the subsequent charge separation, the surface reduction reaction for H 2 generation. In past decades, numerous efforts, including heteroatoms doping, [18,19] heterostructure construction, [20][21][22][23][24][25][26][27][28] and thickness modulation, [29][30][31] have been devoted to enhance the efficiency of the first two processes. However, the HER activity of modified g-C 3 N 4 is limited by insufficient surface catalytic sites, despite of its suitable bandgap for light absorption and chemical stability.…”